Barbeques have steadily evolved over the centuries from the earliest open fires, to simple grills placed over burning charcoal to the modern gas barbeque. While the modern gas barbeque is very convenient as compared to open fire or charcoal cooking, it is often limited by the quality of heat used to cook foods and by the flavour that may be introduced into the cooking foods. Moreover, the modern gas barbeque is often seriously affected by grease fires that may burn or otherwise impart undesirable flavours into cooking foods.
That is, as the modern gas barbeque does not combust wood or charcoal, smoke flavours can generally only be introduced into cooking foods by burning drippings from the food. As such, the modern barbeque can incorporate a variety of heat transfer devices such as lava rocks, ceramic blocks or thin metal plates above the burner, that seek to effectively cause food drippings to burn to create flavour.
Furthermore, the gas flame of a modern gas barbeque does not provide an even heat source as the typical gas barbeque with a gas flame produces a significant temperature gradient between the hottest parts of the flame and those locations where there is no flame. Accordingly, in addition to providing an effective vaporizing surface for juices, the heat transfer devices also seek to effectively distribute heat in order to enable the even cooking of food.
A well known example of a heat transfer device that is limited in its effectiveness is lava rocks. Specifically, while lava rocks are intended to a) distribute the heat from the burners below, and b) collect and vaporize juices from the food within the pores of the rocks, over time, drippings of excess fat and other juices will clog the pores of the lava rocks, resulting in uneven heat distribution and increased flare-ups. As a result, lava rocks require periodic cleaning and/or replacement. Moreover, the porosity of lava rocks renders them relatively poor conductors of thermal energy.
A review of the prior art reveals that while numerous systems have been developed in the past to address various limitations in barbeques, there remains a need for heat transfer devices that continue to improve the quality of barbeque cooking.
For example, U.S. Pat. No. 4,403,597 attempts to improve upon the lava rock system by using a cast iron plate as a heat transfer device. The plate is placed above the burner manifolds of the barbecue and below the grill to radiate heat from the burner to the food above. Food drippings are vaporized or combusted atop the iron plate, the debris from which may be scraped from the surface upon cooling. However, over time, accumulation of charred debris on the plate reduces effective heat distribution to the food. Moreover, although cast iron is a good conductor of thermal energy, it is not a convenient heat transfer device for use in barbecues as it is heavy, cumbersome to manipulate, requires a significant length of time to heat and cool and therefore does not readily facilitate temperature adjustment during use.
U.S. Pat. No. 6,114,666 teaches the use of a glass/ceramic-glass material as a heat transfer device. The glass/ceramic-glass material is placed above the barbecue burner but below the cooking grill which, when heated, acts as an infrared emitter. This material, may however, still collect a buildup of burnt food drippings leading to uneven heating and flare-ups.
Other heat radiating devices are known in the art for distributing heat from a various types of burners. For example, U.S. Pat. No. 1,614,746 teaches the use of wire gauze between the burner manifolds of a broiler to aid in the even distribution of heat to food below. The wire gauze is brought to a temperature at which it becomes luminous thus radiating infrared heat.
In particular, there has been a need for a heat transfer device for barbecues that evenly distributes/radiates thermal energy from the heat source, will quickly respond to changes in heating temperature, while effectively vaporizing food drippings to impart barbecue flavour to food. It is further desired to have a heat transfer that can be readily cleaned of carbon build-up.